Field of the Invention
The present invention relates to mobile communication.
Discussion of the Related Art
3rd generation partnership project (3GPP) long term evolution (LTE) evolved from a universal mobile telecommunications system (UMTS) is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) evolved from the 3GPP LTE.
As disclosed in 3GPP TS 36.211 V10.4.0 (2011-12) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 10)”, 3GPP LTE/LTE-A may divide the physical channel into a downlink channel, i.e., a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH), and an uplink channel, i.e., a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).
Meanwhile, communication between UEs which are physically closed to each other, that is, device to device (D2D) communication) is required due to an increase in user requirements for a social network service (SNS).
The D2D communication may be called a proximity service (ProSe). In addition, a UE that performs the proximity service may be called a ProSe UE. In addition, a link between the UEs used in the D2D communication may be called a sidelink.
For the ProSe, the UE may include a separate RF chain.
However, when the separate RF chain is provided, there is a problem in that power consumption may increase.